Furry Animal Allergen Component Sensitization and Clinical Outcomes in Adult Asthma and Rhinitis

Molecular allergology: a clinical laboratory tool for precision diagnosis, stratification and follow-up of allergic patients

Identification of the molecular culprits of allergic reactions leveraged molecular allergology applications in clinical laboratory medicine. Molecular allergology shifted the focus from complex, heterogeneous allergenic extracts, e.g. pollen, food, or insect venom, towards genetically and immunologically defined proteins available for in vitro diagnosis. Molecular allergology is a precision medicine approach for the diagnosis, stratification, therapeutic management, follow-up and prognostic evaluation of patients within a large range of allergic diseases. Exclusively available for in vitro diagnosis, molecular allergology is nonredundant with any of the current clinical tools for allergy investigation. As an example of a major application, discrimination of genuine sensitization from allergen cross-reactivity at the molecular level allows the proper targeting of the culprit allergen and thus dramatically improves patient management. This review aims at introducing clinical laboratory specialists to molecular allergology, from the biochemical and genetic bases, through immunological concepts, to daily use in the diagnosis and management of allergic diseases.

Advancing diagnostic precision: Unveiling sensitization relationships between cat, dog, and horse allergen molecules

BACKGROUND

Recent advancements in molecular diagnostics have unveiled a multitude of allergen molecules (AMs) associated with animal sensitizations, revealing significant cross- and co-sensitization patterns among these seemingly distinct allergens.

METHOD

We investigated the sensitization profiles of 120 children, sensitized to at least one of the 14 AMs from cat, dog, or horse using the Alex test, employing correlations and hierarchical clusters to explore relationship between sensitizations.

RESULTS

Sensitizations to Fel d 1, Can f 4/5, and Equ c 4 differ from other cat, dog, and horse AM sensitizations, suggesting they may represent genuine sensitizations for their respective animals. High correlations were observed among various AMs, including lipocalins (Can f 1/2/6, Fel d 4/7, and Equ c 1), serum albumins (Fel d 2, Can f 3, and Equ c 3), and uteroglobins (Fel d 1 and Can f_Fd1). Hierarchical clustering of sensitizations identified two similarity clusters and one dissimilarity cluster, providing an estimation of the likelihood of cross-reactivity. Additionally, our method facilitated speculation regarding cross-, co-, or genuine sensitization. Moreover, we noted a potential increase in the number and level of sensitized animal AMs concurrent with increased sensitization to other aeroallergens with advancing age. No significant difference was detected for the presence or absence of various types of allergic comorbidities.

CONCLUSION

Correlations and hierarchical clustering can unveil the extent and magnitude of cross-, co-, and genuine sensitization relationships among animal AMs. These insights can be leveraged to enhance artificial intelligence algorithms, improving diagnostic accuracy through the integration of other measures of sensitization.

Establishment of a homogeneous chemiluminescence immunoassay for cat dander sIgE antibody detection

BACKGROUND

In vitro specific IgE (sIgE) testing has become an important tool for the diagnosis of IgE-mediated allergic diseases. Current methods used to detect allergen sIgE are time consuming and/or expensive. Therefore, a new method was developed for rapid quantitative detection of cat dander-sIgE antibody based on homogeneous chemiluminescence immunoassay.

METHODS

Selection of chemibeads with different chemical groups, and the best Light-initiated chemiluminescence assay (LiCA) analytical mode for cat dander-sIgE detection. To validate and eliminate the interference of IgE on the detection of cat dander-sIgE, concentration of biotinylated anti-human IgE antibody was optimized. For quantification of cat dander-sIgE, a calibration curve was established, and the performance of the assay was evaluated according to clinical guidelines.

RESULTS

Indirect LiCA is the best mode of analysis and biotinylated anti-human IgE antibody at a dilution ratio of 1:250 minimizes IgE interference. The coefficient of variation of the developed LiCA was 1.49% to 4.66%, with an intermediate precision of 6.90% to 8.21%. The LoB, LoD, and LoQ of the assay were 0.023 kUA/L, 0.056 kUA/L and 0.185 kUA/L. The coefficient of correlation (r) between LiCA and ImmounoCAP was 0.9478.

CONCLUSIONS

A cat dander-sIgE quantitation assay based on homogeneous chemiluminescence immunoassay was established, which could be a new reliable analytical tool for the determination of cat dander-sIgE.

Allergenic Activity of Individual Cat Allergen Molecules

More than 10% of the world's population suffers from an immunoglobulin E (IgE)-mediated allergy to cats which is accompanied mainly by respiratory symptoms such as rhinitis and asthma. Several cat allergen molecules have been identified, but their allergenic activity has not been investigated in depth. Purified cat allergen molecules (Fel d 1, Fel d 2, Fel d 3, Fel d 4, Fel d 6, Fel d 7 and Fel d 8) were characterized via mass spectrometry and circular dichroism spectroscopy regarding their molecular mass and fold, respectively. Cat-allergen-specific IgE levels were quantified via ImmunoCAP measurements in IgE-sensitized subjects with (n = 37) and without (n = 20) respiratory symptoms related to cat exposure. The allergenic activity of the cat allergens was investigated by loading patients' IgE onto rat basophils expressing the human FcεRI receptor and studying the ability of different allergen concentrations to induce β-hexosaminidase release. Purified and folded cat allergens with correct masses were obtained. Cat-allergen-specific IgE levels were much higher in patients with a respiratory allergy than in patients without a respiratory allergy. Fel d 1, Fel d 2, Fel d 4 and Fel d 7 bound the highest levels of specific IgE and already-induced basophil degranulation at hundred-fold-lower concentrations than the other allergens. Fel d 1, Fel d 4 and Fel d 7 were recognized by more than 65% of patients with a respiratory allergy, whereas Fel d 2 was recognized by only 30%. Therefore, in addition to the major cat allergen Fel d 1, Fel d 4 and Fel d 7 should also be considered to be important allergens for the diagnosis and specific immunotherapy of cat allergy.

Factors associated with aeroallergen testing among adults with asthma in a large health system

Background

Aeroallergen testing informs precision care for adults with asthma, yet the epidemiology of testing in this population remains poorly understood.

Objective

We sought to identify factors associated with receiving aeroallergen testing, the results of these tests, and subsequent reductions in exacerbation measures among adults with asthma.

Methods

We used electronic health record data to conduct a retrospective, observational cohort study of 30,775 adults with asthma who had an office visit with a primary care provider or an asthma specialist from January 1, 2017, to August 26, 2022. We used regression models to identify (1) factors associated with receiving any aeroallergen test and tests to 9 allergen categories after the index visit, (2) factors associated with positive test results, and (3) reductions in asthma exacerbation measures in the year after testing compared with before testing.

Results

Testing was received by 2201 patients (7.2%). According to multivariable models, receiving testing was associated with having any office visit with an allergy/immunology specialist during the study period (odds ratio [OR] = 91.3 vs primary care only [P < .001]) and having an asthma emergency department visit (OR = 1.62 [P = .004]) or hospitalization (OR = 1.62 [P = .03]) in the year before the index visit. Age 65 years or older conferred decreased odds of testing (OR = 0.74 vs age 18-34 years [P = .008]) and negative test results to 6 categories (P ≤ .04 for all comparisons). Black race conferred increased odds of testing (OR =1.22 vs White race [P = .01]) and positive test results to 8 categories (P < .04 for all comparisons). Exacerbation measures decreased after testing.

Conclusion

Aeroallergen testing was performed infrequently among adults with asthma and was associated with reductions in asthma exacerbation measures.

Molecular sensitization patterns to cat and dog allergens in Lithuanian children population

Background

Over the last few decades, there was observed an increase of asthma and allergic rhinitis cases caused by allergy to pets.

Objective

This study aimed to analyze molecular sensitization patterns to dog and cat allergens in Lithuanian children who were experiencing allergy-like symptoms.

Materials and methods

A total of 574 children (0-18 years) were tested for allergen-specific immunoglobulin E (sIgE) levels with ALEX2 (ALEX2®, Allergy Explorer Test System). Positive sera were further analyzed for sensitization to cat (Fel d 1, Fel d 2, Fel d 4, and Fel d 7) and dog (Can f 1, Can f 2, Can f 3, Can f 4, Can f 5, and Can f 6) allergen components.

Results

Two hundred forty-seven children tested positive (sIgE ≥0.3 kUA/L) to at least 1 dog or cat allergen component. There were 61.1% children sensitized to components from both sources, 29.2% - exclusively to cat, and 9.7% - to dog components. The major sensitizers were Fel d 1 (84.8%) and Can f 1 (59.4%). There were 42.9% patients sensitized to 3 or more different mammalian protein families and 40.4% - to 3 or more lipocalins. There were 5.7% of children sensitized both to Fel d 1 + Fel d 4 and Can f 1/2 + Can f 5, indicating the high risk of severe asthma. Monosensitization to Fel d 1 was the dominant pattern among Lithuanian children (26.3%).

Conclusion

The majority of children were cat/dog-polysensitized, although sensitization only to cat allergens was most observed. Extensive molecular profiling can be an useful tool for accurate true sensitization diagnosis and prognosis of disease severity.

GEMA 5.3. Spanish Guideline on the Management of Asthma

The Spanish Guideline on the Management of Asthma, better known by its acronym in Spanish GEMA, has been available for more than 20 years. Twenty-one scientific societies or related groups both from Spain and internationally have participated in the preparation and development of the updated edition of GEMA, which in fact has been currently positioned as the reference guide on asthma in the Spanish language worldwide. Its objective is to prevent and improve the clinical situation of people with asthma by increasing the knowledge of healthcare professionals involved in their care. Its purpose is to convert scientific evidence into simple and easy-to-follow practical recommendations. Therefore, it is not a monograph that brings together all the scientific knowledge about the disease, but rather a brief document with the essentials, designed to be applied quickly in routine clinical practice. The guidelines are necessarily multidisciplinary, developed to be useful and an indispensable tool for physicians of different specialties, as well as nurses and pharmacists. Probably the most outstanding aspects of the guide are the recommendations to: establish the diagnosis of asthma using a sequential algorithm based on objective diagnostic tests; the follow-up of patients, preferably based on the strategy of achieving and maintaining control of the disease; treatment according to the level of severity of asthma, using six steps from least to greatest need of pharmaceutical drugs, and the treatment algorithm for the indication of biologics in patients with severe uncontrolled asthma based on phenotypes. And now, in addition to that, there is a novelty for easy use and follow-up through a computer application based on the chatbot-type conversational artificial intelligence (ia-GEMA).

Sensitization patterns to cat molecular allergens in subjects with allergic sensitization to cat dander

BACKGROUND

The use of molecular allergology has increasingly become common in the diagnosis and management of allergic diseases. However, there is still a lack of data on cat molecular allergens in adults. Therefore, we aimed to uncover the sensitization patterns to cat molecular allergens.

METHODS

Participants were recruited from the West Asthma Sweden Study, a population-based study enriched with asthma subjects aged 16-75 years. Of 1872, 361 individuals were positive for cat dander immunoglobulin E and were further analysed for cat molecular allergens (Fel d 1/2/4/7). Sensitization patterns were classified as monosensitization, polysensitization, and concomitant sensitization, and were related to demographic and clinical measurements.

RESULTS

Among cat-sensitized subjects, 84.2% were sensitized to secretoglobin, while 42.4% were sensitized to lipocalins. Nearly half of the subjects were monosensitized to Fel d 1. Polysensitization was observed in 20.2%, and concomitant sensitization to protein families was seen in 7.2%. Asthma prevalence, cat exposure, and rural living were associated with poly- and concomitant sensitization to protein families. Concomitant sensitization to single allergens was more common in those with asthma than in those without, while concomitant sensitization to both Fel d 1 and Fel d 4 was the most common pattern in individuals with asthma. Sensitization patterns also differed according to cat ownership and the degree of urbanization.

CONCLUSION

Sensitization to molecular allergens was observed in 90.9% of cat-sensitized subjects and showed variations across participants' background characteristics and the presence of asthma. Identification of sensitization patterns to cat allergens might provide better characterization of cat-allergic subjects.

Indoor-air purification by photoelectrochemical oxidation mitigates allergic airway responses to aerosolized cat dander in a murine model

Portable air purifiers help improve indoor air quality by neutralizing allergens, including animal dander proteins. However, there are limited in-vivo models to assess the efficacy of these devices. Here, we developed a novel animal model of experimental asthma using aerosolized cat dander extract (CDE) exposure and compared the efficacy of select air purification technologies. Mice were exposed to CDE aerosols for 6 weeks in separate custom-built whole-body exposure chambers equipped with either a photoelectrochemical oxidative (PECO) Molekule filtration device (PFD) or a HEPA-assisted air filtration device (HFD) along with positive (a device with no filtration capability) and negative controls. Compared to the positive control group, the CDE-induced airway resistance, and plasma IgE and IL-13 levels were significantly reduced in both air purifier groups. However, PFD mice showed a better attenuation of lung tissue mucous hyperplasia and eosinophilia than HFD and positive control mice, indicating a better efficacy in managing CDE-induced allergic responses. Cat dander protein destruction was evaluated by LCMS proteomic analysis, which revealed the degradation of 2731 unique peptides on PECO media in 1 h. Thus, allergen protein destruction on filtration media enhances air purifier efficacy that could provide relief from allergy responses compared to traditional HEPA-based filtration alone.

An update on the prevalence and diagnosis of cat and dog allergy - Emphasizing the role of molecular allergy diagnostics

The clinical presentation of cat and dog allergy vary from discomfort caused by rhinoconjuncitivitis to severe asthma. Exposure to allergens from these animals is ubiquitous and allergic sensitization to cat or dog affect up to 25% of all children and adults, but allergic sensitization does not always cause symptoms. The introduction of molecular-based allergy diagnostics has improved the possibility to characterize the allergic patient in greater detail. However, the full clinical potential of using molecular allergology in the diagnosis, characterization and treatment of patients with allergy to cats and dogs has not yet been established, although significant progress has been made during the last decade, which will be reviewed in detail in this paper.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

The association between specific IgE antibodies to component allergens and allergic symptoms on dog and cat exposure among Korean pet exhibition participants

Background

Component resolved diagnostics (CRD) in dog and cat allergy is not sufficiently investigated, especially regarding new components such as Can f 4, Can f 6, and Fel d 7. The purpose of this study is to evaluate the potential role of CRD with new components in predicting allergic symptoms on dog and cat exposure.

Methods

Among 552 Korean adults who participated in a pet exhibition and completed questionnaires regarding exposure to dog or cat and allergic symptoms, 522 were venipunctured for measurement of IgE and IgG4 antibody concentration against dog and cat dander extract and underwent skin prick test (SPT). In 238 individuals who were sensitized for both dog and cat dander extract, the dog IgE components (Can f 1–6) and the cat components (Fel d 1/2/4/7) were analyzed.

Results

An increasing number of sensitizing components was associated with the likelihood of having any allergic symptoms (P < 0.001 for dog and P < 0.01 for cat), and those of asthma (P < 0.01 for dog and P < 0.05 for cat) and rhinoconjunctivitis (P < 0.001 for dog and P < 0.05 for cat). Pairwise correlation of IgE levels was r = 0.56 (P < 0.001) for Can f 6 and Fel d 4, r = 0.74 (P < 0.001) for Can f 1 and Fel d 7 and r = 0.84 (P < 0.001) for Can f 3 and Fel d 2.

Conclusions

Polysensitization to dog and cat allergen components is associated with high likelihood of having allergic symptoms during exposure to dogs and cats. Cross-reactivity between dog and cat allergen components is also identified. CRD has a potential in fine-tuning prediction for allergic symptoms on dog and cat exposure.

In-home environmental exposures predicted from geospatial characteristics of the built environment and electronic health records of children with asthma

PURPOSE

Children may be exposed to numerous in-home environmental exposures (IHEE) that trigger asthma exacerbations. Spatially linking social and environmental exposures to electronic health records (EHR) can aid exposure assessment, epidemiology, and clinical treatment, but EHR data on exposures are missing for many children with asthma. To address the issue, we predicted presence of indoor asthma trigger allergens, and estimated effects of their key geospatial predictors.

METHODS

Our study samples were comprised of children with asthma who provided self-reported IHEE data in EHR at a safety-net hospital in New England during 2004-2015. We used an ensemble machine learning algorithm and 86 multilevel features (e.g., individual, housing, neighborhood) to predict presence of cockroaches, rodents (mice or rats), mold, and bedroom carpeting/rugs in homes. We reduced dimensionality via elastic net regression and estimated effects by the G-computation causal inference method.

RESULTS

Our models reasonably predicted presence of cockroaches (area under receiver operating curves [AUC] = 0.65), rodents (AUC = 0.64), and bedroom carpeting/rugs (AUC = 0.64), but not mold (AUC = 0.54). In models adjusted for confounders, higher average household sizes in census tracts were associated with more reports of pests (cockroaches and rodents). Tax-exempt parcels were associated with more reports of cockroaches in homes. Living in a White-segregated neighborhood was linked with lower reported rodent presence, and mixed residential/commercial housing and newer buildings were associated with more reports of bedroom carpeting/rugs in bedrooms.

CONCLUSIONS

We innovatively applied a machine learning and causal inference mixture methodology to detail IHEE among children with asthma using EHR and geospatial data, which could have wide applicability and utility.

Cat allergy in children and the effect of the COVID-19 pandemic

Background: Cat allergen is among the most common household allergens and can cause respiratory allergies and anaphylaxis in children. Objective: The aim of this study was to evaluate the characteristics of cat allergies in children and the impact of the coronavirus disease 2019 (COVID-19) pandemic on these characteristics. Methods: The study included pediatric patients with cat allergen sensitization demonstrated by skin-prick test (SPT) over a period of 2 years: 1 year before and 1 year during the pandemic. Demographic data, clinical features, and laboratory findings were evaluated from the patients' records. Results: Of 7428 SPTs performed, 566 patients (7.6%) were sensitized to cat allergen (56% boys; median age, 11 years). Fifty-eight percent of the patients (n = 329) presented during the pandemic period, 44.5% (n = 252) had symptoms with cat exposure, and 9% (n = 51/566) had anaphylaxis. Allergic rhinitis and asthma were present in 76% (n = 431) and 46.6% (n = 264) of the patients, respectively. When compared to prepandemic period, patients who presented during the pandemic had higher rates of cat sensitization (15% in pandemic group versus 4.4% in prepandemic group of all SPTs performed; p < 0.05), cat ownership (29.1% versus 13.9%; p < 0.001), and symptoms on cat exposure (51% versus 34%; p < 0.001). Factors that predicted symptom development in the patients who were cat sensitized were induration > 5 mm on SPT (odds ratio [OR] 1.9 [95% confidence interval {95% CI}], 1.1-3.2), cat ownership (OR 9.2 [95% CI, 4.9-17.3]), close contact with a cat owner (OR 7.1 [95% CI, 4-12]), allergic rhinitis (OR 3.1 [95% CI, 1.6-5.8]), conjunctivitis (OR 4.7 [95% CI, 2-10]), and atopic dermatitis (OR 2.2 [95% CI, 1-4.7]). Conclusion: We observed an increase in the prevalence of cat allergy among children during the COVID-19 pandemic. Care must be taken in terms of anaphylaxis in patients who were cat sensitized.

Complex IgE sensitization patterns in ragweed allergic patients: Implications for diagnosis and specific immunotherapy

Background

Ragweed (Ambrosia artemisiifolia) is one of the most important allergen sources, worldwide, causing severe respiratory allergic reactions in late summer and fall, in sensitized patients. Amb a 1 has been considered as the most important allergen in ragweed but 12 ragweed pollen allergens are known. The aim of our study was to investigate IgE reactivity profiles of ragweed allergic patients and to associate them with clinical symptoms.

Methods

IgE sensitization profiles from clinically well-characterized ragweed allergic patients (n = 150) were analyzed using immunoblotted ragweed pollen extract. Immunoblot inhibition experiments were performed with two Amb a 1 isoforms and CCD markers and basophil activation experiments were performed with IgE serum before and after depletion of Amb a 1-specific IgE.

Results

By IgE-immunoblotting 19 different IgE reactivity patterns with and without Amb a 1-sensitization were found. The majority of patients (>95%) suffered from rhino-conjunctivitis, around 60% reported asthma-like symptoms and about 25% had skin reactions. Patients with complex IgE sensitization profiles tended to have more clinical symptoms. Serum with and without Amb a 1-specific IgE induced basophil activation.

Conclusions

Ragweed pollen allergic patients exhibit complex IgE reactivity profiles to ragweed allergens including Amb a 1 isoforms and cross-reactive carbohydrates indicating the importance of Amb a 1 isoforms and additional allergens for diagnosis and allergen-specific immunotherapy of ragweed allergy.

Molecular Allergen-Specific IgE Recognition Profiles and Cumulative Specific IgE Levels Associated with Phenotypes of Cat Allergy

Cat allergy is a major trigger factor for respiratory reactions (asthma and rhinitis) in patients with immunoglobulin E (IgE) sensitization. In this study, we used a comprehensive panel of purified cat allergen molecules (rFel d 1, nFel d 2, rFel d 3, rFel d 4, rFel d 7, and rFel d 8) that were obtained by recombinant expression in Escherichia coli or by purification as natural proteins to study possible associations with different phenotypes of cat allergy (i.e., rhinitis, conjunctivitis, asthma, and dermatitis) by analyzing molecular IgE recognition profiles in a representative cohort of clinically well-characterized adult cat allergic subjects (n = 84). IgE levels specific to each of the allergen molecules and to natural cat allergen extract were quantified by ImmunoCAP measurements. Cumulative IgE levels specific to the cat allergen molecules correlated significantly with IgE levels specific to the cat allergen extract, indicating that the panel of allergen molecules resembled IgE epitopes of the natural allergen source. rFel d 1 represented the major cat allergen, which was recognized by 97.2% of cat allergic patients; however, rFel d 3, rFel d 4, and rFel d 7 each showed IgE reactivity in more than 50% of cat allergic patients, indicating the importance of additional allergens in cat allergy. Patients with cat-related skin symptoms showed a trend toward higher IgE levels and/or frequencies of sensitization to each of the tested allergen molecules compared with patients suffering only from rhinitis or asthma, while there were no such differences between patients with rhinitis and asthma. The IgE levels specific to allergen molecules, the IgE levels specific to cat allergen extract, and the IgE levels specific to rFel d 1 were significantly higher in patients with four different symptoms compared with patients with 1–2 symptoms. This difference was more pronounced for the sum of IgE levels specific to the allergen molecules and to cat extract than for IgE levels specific for rFel d 1 alone. Our study indicates that, in addition to rFel d 1, rFel d 3, rFel d 4, and rFel d 7 must be considered as important cat allergens. Furthermore, the cumulative sum of IgE levels specific to cat allergen molecules seems to be a biomarker for identifying patients with complex phenotypes of cat allergy. These findings are important for the diagnosis of IgE sensitization to cats and for the design of allergen-specific immunotherapies for the treatment and prevention of cat allergy.

Human allergy to cats: A review for veterinarians on prevalence, causes, symptoms and control

PRACTICAL RELEVANCE

Human allergy to cats affects a substantial and growing proportion of the global population, and cat allergy is regarded as the third most common cause of human respiratory allergies, and the second most common indoor cause. Veterinarians will frequently encounter owners who are cat-allergic, and having an understanding of this disease and the methods available to help control the allergy will assist them in giving appropriate advice, alongside human healthcare professionals.

AIM

The aim of this review is to summarise currently available data on the prevalence, causes, symptoms and control of human allergy to cats. In terms of managing cat allergy, the emphasis is on reviewing current and emerging modalities to reduce environmental exposure to cat allergens rather than on pharmacotherapy or immunotherapy, as it is in these areas in particular that the veterinarian may be able to offer help and advice to complement that of human healthcare professionals.

EVIDENCE BASE

The information in this review is drawn from the current and historical literature on human allergy to cats, and approaches to reduce exposure to cat allergens and manage symptoms of cat allergy.

Molecular sensitization patterns in animal allergy: Relationship with clinical relevance and pet ownership

BACKGROUND

In vitro diagnosis using single molecules is increasingly complementing conventional extract-based diagnosis. We explored in routine patients with animal allergy to what extent molecules can explain polysensitization and identify primary sensitizers and how individual IgE patterns correlate with previous pet ownership and clinical relevance.

METHODS

Serum samples from 294 children and adults with suspect allergic rhino-conjunctivitis or asthma and a positive skin prick test to cat, dog and/or horse were tested by ImmunoCAP for IgE antibodies against eleven different allergens from cat (Fel d 1,2,4,7), dog (Can f 1,2,3,4,5,6) and horse (Equ c 1).

RESULTS

Patients monosensitized to cat (40.8%) or dog (6.1%) showed simple IgE patterns dominated by Fel d 1 (93%) and Can f 5 (67%), respectively. Double-sensitization to cat+dog (25.9%), cat+horse (5.4%) and polysensitization (20.7%) was associated with an increasing prevalence of the cross-reactive lipocalins Fel d 4/Can f 6/Equ c 1 and Fel d 7/Can f 1. While these lipocalins were not reliable markers for genuine sensitization per se, comparison of sIgE levels may give a clue on the primary sensitizer. Sensitizations to dog appeared to result from cross-reactivity with cat in 48%, with half of these sensitizations lacking clinical relevance. Individual sensitization patterns strongly mirrored current or previous pet ownership with the exception of Fel d 1 which regularly caused sensitization also in non-owners.

CONCLUSIONS

Allergen components can reasonably illuminate the molecular basis of animal (poly)sensitization in the majority of patients and are helpful in distinguishing between primary sensitization and sometimes less relevant cross-reactivity.

How molecular allergology can shape the management of allergic airways diseases

PURPOSE OF REVIEW

In allergy, personalized medicine passes through the assessment of molecular allergens sensitization profiles. Such technique may help to better diagnose and treat patients suffering from allergic respiratory diseases.

RECENT FINDINGS

Different laboratory tests are available today to assess sensitization to molecular allergens, from singleplex assays, to unspecific, screening multiplex assays, mainly performed through microarrays or macroarrays. It is important to collect both results from specific IgE toward allergen extracts and toward molecular allergens, to collect the most complete information on the patient's profile, and therefore to highlight genuine sensitization, and exclude cross-reaction and sensitization because of pan-allergens. Being able to know the exact molecular sensitization profile of the patient, also helps predicting the possible evolution of the disease, and targeting the most appropriate allergen immunotherapy treatment to prescribe.

SUMMARY

Even though a cost-effective analysis of running multiple assays in allergic patients has not been performed yet, such technique proved to be more efficient in detecting the appropriate treatment in each patient and in analyzing the true sensitization profile in patients suffering from allergic rhinitis, conjunctivitis, and asthma.

Component-resolved diagnostics in pet allergy: Current perspectives and future directions

Furry mammals kept as pets are important allergen sources. The prevalence of sensitization to dander from various animals appears to be increasing worldwide. Several mammalian allergens from diverse species and distinct protein families have been characterized, and some are available for component-resolved diagnostics (CRD). This review presents an overview of mammalian aeroallergens, with a focus on cat, dog, and horse allergens. The potential of CRD in fine-tuning the diagnostic workup following traditional methods based on whole- allergen extracts and allergen immunotherapy is discussed. The review highlights the clinical utility of CRD, particularly as a marker/predictor of increased asthma risk and disease severity. Finally, several perspectives of the future implications of CRD are offered in the context of furry animal allergens.

Developments allergy in 2019 through the eyes of Clinical and Experimental Allergy, Part II clinical allergy

In the second of two linked articles, we describe the development in clinical as described by Clinical & Experimental Allergy and other journals in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered. In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered.

Connectivity patterns between multiple allergen specific IgE antibodies and their association with severe asthma

BACKGROUND

Allergic sensitization is associated with severe asthma, but assessment of sensitization is not recommended by most guidelines.

OBJECTIVE

We hypothesized that patterns of IgE responses to multiple allergenic proteins differ between sensitized participants with mild/moderate and severe asthma.

METHODS

IgE to 112 allergenic molecules (components, c-sIgE) was measured using multiplex array among 509 adults and 140 school-age and 131 preschool children with asthma/wheeze from the Unbiased BIOmarkers for the PREDiction of respiratory diseases outcomes cohort, of whom 595 had severe disease. We applied clustering methods to identify co-occurrence patterns of components (component clusters) and patterns of sensitization among participants (sensitization clusters). Network analysis techniques explored the connectivity structure of c-sIgE, and differential network analysis looked for differences in c-sIgE interactions between severe and mild/moderate asthma.

RESULTS

Four sensitization clusters were identified, but with no difference between disease severity groups. Similarly, component clusters were not associated with asthma severity. None of the c-sIgE were identified as associates of severe asthma. The key difference between school children and adults with mild/moderate compared with those with severe asthma was in the network of connections between c-sIgE. Participants with severe asthma had higher connectivity among components, but these connections were weaker. The mild/moderate network had fewer connections, but the connections were stronger. Connectivity between components with no structural homology tended to co-occur among participants with severe asthma. Results were independent from the different sample sizes of mild/moderate and severe groups.

CONCLUSIONS

The patterns of interactions between IgE to multiple allergenic proteins are predictors of asthma severity among school children and adults with allergic asthma.

Nasal Provocation Test with Cat and Dog Extracts: Results according to Molecular Components

Background

IgE sensitization (atopy) to pets is commonly evaluated using pet dander extracts. However, the diagnosis by components seems to be more adequate to evaluate the clinical relevance (allergy) of sIgE sensitization.

Objective

To study the association between IgE sensitization to pet allergen components and clinical symptoms. Methodology. Dander extracts and sIgE levels to pet components (Can f 1, Can f 2, Can f 3, Can f 5, Fel d 1, Fel 2, and Fel 4) were measured in a rhinitis group (n = 101) and a control group (n = 101) and a control group (.

Results

Dog (34.6% vs. 23.5%) and cat dander (26.7% vs. 8.8%, p = 0.05) IgE sensitization was frequent among rhinitis and no-rhinitis subjects, and it was similar to dog (29.7% vs. 20.5%) and cat (18.8% vs. 8.8%) components. Polysensitization for dog (3.1, 95% CI: 1.5 to 6.1, p = 0.05) IgE sensitization was frequent among rhinitis and no-rhinitis subjects, and it was similar to dog (29.7% vs. 20.5%) and cat (18.8% vs. 8.8%) components. Polysensitization for dog (3.1, 95% CI: 1.5 to 6.1, p = 0.05) IgE sensitization was frequent among rhinitis and no-rhinitis subjects, and it was similar to dog (29.7% vs. 20.5%) and cat (18.8% vs. 8.8%) components. Polysensitization for dog (3.1, 95% CI: 1.5 to 6.1.

Conclusions

Sensitization to pet dander extract identifies atopic patients, but its utility to predict clinical relevance is poor. Allergenic components could help to define the clinical relevance of sensitization to furry animals and could reduce the need for provocation test.

The Journal of Allergy and Clinical Immunology: In Practice 2019 Highlights

This article provides highlights of the clinically impactful original studies and reviews published in The Journal of Allergy and Clinical Immunology: In Practice in 2019 on the subjects of anaphylaxis, asthma, dermatitis, drug allergy, food allergy, immunodeficiency, immunotherapy, rhinitis/sinusitis, and urticaria/angioedema/mast cell disorders. Within each topic, practical aspects of diagnosis and management are emphasized. Treatments discussed include lifestyle modifications, allergen avoidance therapy, positive and negative effects of pharmacologic therapy, and various forms of immunologic and desensitization management. We designed this review to help readers consolidate and use this extensive and practical knowledge for the benefit of their patients.

Keep the cat, change the care pathway: A transformational approach to managing Fel d 1, the major cat allergen

Background

Allergies to cats are the most common animal‐origin allergy, and affect approximately 1 in 5 adults worldwide. The prevalence of allergy to furry animals has been increasing, and allergy to cats is a major risk factor for the development of asthma and rhinitis. The diagnosis of cat allergy is now well established. The exact significance of component‐resolved diagnosis in the diagnosis of cat allergy remains to be fully understood. Allergen avoidance is effective but often has a psychologic impact. Allergen immunotherapy is not well demonstrated. There is a need for innovative approaches to better manage cat allergens. Next‐generation care pathways for asthma and rhinitis will define the place of cat allergen avoidance.

Methods and Results

This manuscript, based on content presented at the European Academy of Allergy and Clinical Immunology Congress 2019, provides information on the prevalence and impact of cat allergies and the molecular biology of Fel d 1, the major cat allergen.

Discussion

The authors present the scientific basis of a novel care pathway that utilizes anti‐Fel d 1 IgY antibodies to safely and effectively neutralize Fel d 1 after its production by the cat but before human exposure.

Conclusion

Efficacy of a feline diet with an egg product ingredient containing anti‐Fel d 1 IgY antibodies was demonstrated in vitro, ex vivo, and in vivo, and further validated by a pilot exposure study involving cat‐allergic human participants.